This invention is directed to a channel equalizer and method for cancelling ghosts from a transmitted communication signal. A television signal is exemplary of the type of signal from which ghosts are cancelled by the present invention.
It is well known that many types of transmitted signals acquire ghosts on their way to a receiver. Signals which are broadcast over the air generally acquire ghosts as a result of the transmitted signal being reflected by a building or other object. Signals which are transmitted via cables can acquire ghosts due to reflections from improper terminations and other factors. Whatever the source of the ghosts, the signal picked up at the receiver is adversely affected.
In the television industry, various ghost cancelling proposals have been made. Some such proposals require the use of transversal filters in a so-called feed-forward network. Others require the use of complex filters in a network around which a feedback path is established. These and other such proposals either have not worked well, have been too complex, or both. In addition, some such proposals require circuitry which is not unconditionally stable. Hence, ghost cancelling circuits have not been included in commercial television receivers or in other high volume products.